The Boa Constrictor snake myth: busted

Remember all those times you were taught that a boa constrictor kills its prey by suffocating them? Well, it turns out it's not actually true.

That increased heart rate you had when you held a boa at the zoo and felt it tighten around your arm? That's actually a bit of a clue as to what's really going on.

Scientists from Dickinson College in Pennsylvania have discovered that snakes actually kill their victims by cutting off the blood flow to the animal's vital organs. This "shut off" rapidly destroys the tissue of the heart, liver and brain, with the latter often causing small animals, such as rodents, to "pass out within seconds", enabling the snake to have a much easier job of finishing it off.

The findings, published in the Journal of Experimental Biology, were obtained by giving anaesthetised rats to snakes and measuring a host of body activity including blood samples, blood pressure and heart rates before, after and at the moment of death. Similar studies have been done before but this is the first to test for circulatory arrest directly from the body of the prey to confirm the theory.

Lead researcher Prof Scott Boback explained that the original myth of suffocation could simply be an unintended side effect of the snake's main aim of blood flow restriction, saying, "If the snake is wrapping around the chest, it could also be limiting breathing, too. But an absence of blood flow will cause death more rapidly than suffocation. So it could be considered a much more precise and efficient method of killing."

He added, "The thing I find fascinating is that all snakes have is their mouth to engage with prey. A [constrictor] has to hold a potentially dangerous animal right next to it. And that animal's fighting for its life, so it will absolutely take chunks out the snake if it can."

A previous study by the same group also made the discovery that snakes were able to sense their prey's heartbeat so that when it stopped, they eased off on the squeezing in order to save energy. What a clever animal.

And, because it's brilliant, here's a video of Steve Irwin getting licked by the most dangerous snake in the world.